Self-closing vent assembly for a sealed container

ABSTRACT

A battery casing fitted at its top with a central terminal has a cantilever spring traversed by that terminal and clamped between the head thereof and an underlying O-ring to exert pressure upon a resilient plug member projecting from a recess alongside the terminal, this plug member overlying the exit end of a vent hole passing through the casing top. Rotation of the spring from its normal position allows removal of the plug member for the introduction of fresh electrolyte into the battery via the vent hole.

United States Patent [72] Inventor Nurl Kellen Jackson Heights, NJ. I 785.496

Dec. 20. I968 July 27, I971 Yardley International Corp. New York, NX.

[22] Filed (45] Patented [73] Assignee [54] v SELF-CLOSING VENT ASSEMBLY FOR A SEALED com/11111111 NChhsJllnwingl-lgs. 1 s21 u.s.c1. 220/4411, 136/162, l36/l78 [511 -1.0 nesasms so vnintms mn 136/178. .-l62; 222/479;220/44;2l5l56 I Iss1 7 lam-meme I uNrr1-:n sn'res rams 2,060,199 ""936 Drummond l36/l36.l

6/1943 Adams 2,322.2 l0 l36/l00 M 2.766,408 l0/i956 Georgiev et al.... 220/44 X 2.38L368 4/1959 Hancock 220/44 X 3.320.097 5/ i967 Sugalslti 220/44 X 2.649,494 8/ I953 Martin 136/] 78.7 FOREIGN PATENTS 629,820 9/ i949 Great Britain 220/44 981.671 1/195 France 220/44 Primary Examiner-Raphael H. Schwartz Anorney- Karl F. Ross ABSTRACT: A battery casing fitted at its top with a central terminal has a cantilever spring traversed by that terminal and clamped between the head thereof and an underlying O-ring to exert pressure upon a resilient plug member projecting from a recess alongside the terminal, this plug member overlying the exit end of a vent hole passing through the casing top. Rotation of the spring from its normal position allows removal of the plug member for the introduction of fresh electrolyte into the battery via the vent hole.

PATENTEU JUL27 I971 3, 595,429

sum 2 0r 3 33 26 I8 202 22 I4 I5 25 M 7/ FIG. 2

INVENTOR.

NURI KOHEN BY x774 SELF-CLOSING VENT ASSEMBLY FOR A SEALED CONTAINER I This invention relates to devices for releasing high-pressure gases generated in hermetically sealed enclosures without destroyingthe pressuretight integrity of the container. More specifically, itrelates to a self-closing pressure-vent assembly for a sealed battery.

Rechargeable batteries, e.g. those of the silver-zinc, nickelcadmium or silvercadmium types, may generate gases during the charging and discharging process. At times the gas pressure may rise to objectionably high values capable of exploding the can or harming the contents in the absence of a safety valve. However, the various applications in which these devices are usedrequire that the cellsbe hermetically sealed.

between the center terminal and the closure aperture through which the terminal stem passes to make contactwith the cell electrode. A resilient strip or an O-ring-cornpressed between two surfaces providesa normally closed seal which stops the high-pressure gas exiting through the previously mentioned space. As the pressureincr eases, the gasultimately escapes between the strip or the'O-ring, as thecase may be, and the top surface. But the topsurface is the. terminal point to which external connections are .made, and any such connections destroy the delicate spring balance which is designed to release thegas pressure when it reaches a predeterminedlevel.

A second major disadvantage of existing types is that the escape of high-pressure gases will ultimately reduce the amount of electrolyte and consequently the cell life. Since the closure is assembled into the container as a one-time installation and the terminal through the vent aperture is a permanen t-typeconnection, it is not possible to refill the containerafter the'closure isinstalled in hermetically sealed casin gs iwjitlrthe present resealable vent designs.

It is accordingly an object of this invention to provide an improved self-resealing pressure-vent assembly for a sealed container.

' It is another object of this invention to provide a selfresealable pressure vent assembly fora sealed-battery in which an external connection can be made to a terminal without at"- fecting the level at which high-pressure gas is released to the atmosphere. I

It is a further object to providea selfresealable pressurevent assembly for a sealed container which can be filled or refilled after the closure is permanently installed in the container. These and additional objects and features are realized in accordance with my present inventionby providing a vent hole forming part of a connector lug placed around this stem and against the undersurface of the closure. The compression of through 'an otherwise conventional closure or casing top to give passage to high-pressure gases for releasing them to the atmosphere. A resilient disc or other deformable plug member 1 ispositioned in a recess over the exit atmosphereend of the vent to seal it under pressure from a cantilever spring overlying it under stress. The spring is swingably clamped between the head -of a boldlike stud or fastening member and an under-- serve as ,one terminal. The entire assembly is secured to'the v closure by flaring the free endof the stem over a rigid washer the O-ring seals off any leakage path through the aperture in which the fastener stem passes through the closure. The cj m. pression of the resilient plugagainst the vent exit determines the sealing force which must be overcome by thegas pressure inside the container. When objectionably high'gas pressure is generated, its action on the underside of the disc overcomes the sealing force and breaks the seal, releasin g the high pressure gas to the atmosphere. The continuing-spring pressure then reseals the vent until the container pressure builds 'up again to the objectionable level for which the spring tension is designed. The pivoted springfaste'ning allows the spring to be rotated away from the vent and the disc tobe removed and permits filling orrefilling the container after the closure has been permanently installed in the container.

In the accompanying drawing:

FIG. I is a perspective view of a sealed container with a portion removed to revel an embodiment of the self-resealing pressure-vent assembly embodying the present invention;

FIG. 2a is a plan view of the self-rescaling pressure-vent assembly of FIG. 1; 1

FIG. 2b is an elevational section of the self-rescaling pressure-vent assembly of FIG. 1;

foi' 'the vent exit through a top cover 8 to make'contact with the internal electrade. of cell 11. The internal structure of the cell is not shown, as it is not necessary to an understandingof the invention. A conductive lug 30 traversing a sealing member or closure I3 is joined by a suitable weld 9 to connector 7. Before assembly, connector 7 which is a flexible copper strip stands up from container 10 to provide room for the welding operation. When closure 13 is assembled into container 10, connector 7 bends over as shown. Cylindrically shouldered closure 13 made from a suitable insulating material and having a resilient gasket of sheet material 15 around its periphery, is seated over the crimped portion 12 of the container over the cell 11, and the top 14 of the container is spun over gasket 15 and the top of closure 13 to form a hermetic seal between container and closure.

FIGS. 2a and 2b illustrate the principle of a preferred embodiment of the self-rescaling pressure-vent assembly according to the present invention in more detail. The closure 13 is cylindrical and has a shoulder 34"which rests on the crimpedin portion .12 of container 10. For battery applications, the closurewill be fabricated from a suitable electrically insulating material such as Teflon.

A vent hole 32 passes eccentrically through the closure 13 to-discharge objectionably high-pressure gas from the interior of the container 10 to the atmosphere through the exit end 33 of this vent, the end 33 opening into a cylindrical recess I4 in the relatively smooth outer surface 25 of closure 13. Exit 33' of vent 32 is in the form of an annularor semitoroidal rim which is raised above the bottom of recess 14 to provide a sealing surface for a resilient disc 15.

Resilient disc 15, preferablymade of neoprene, is shown in FIG.2b resting on ventexit end 33. The inner circumference of recess prevents the cylindrical resilient disc 15 from moving laterally off vent exit end 33. A leaf spring 16 exerts a downward force on resilient disc 15 to prevent it from escaping out of recess 14.

An aperture or bore 27 passes centrally through theclosure 13. A second cylindrical recess depression 31 concentric with aperture 27 is provided in the outer surface 25 to accommodate resilient O-ring 26 also preferably of neoprene.

Leaf spring 16 has a hole 21 near its center which fits around the stem 28 and under the shoulder 17 a terminal stud or fastener 20. For battery applications, spring 16' is made from a suitably conductive elastic material such as beryllium copper. To facilitate the attachment of terminal leads or tabs, a lug portion 24 of spring 16 has a bend 22 upwards and away from the closure surface 25, a connecting hole 23 being provided in the lug 24.

Fastener 20 has a head portion 18 on its stem 28. For battery applications where fastener 20 makes a connection with an internal electrode through the closure, the fastener will be made from a suitable conductive material such as copper.

The depth of recesses 14 and 31 and the thickness of resilient disc and O-ring 26 are such that when disc 15 and O-ring 26 lie in their normal uncompressed condition on vent exit end 33 and the bottom of recess 31 respectively, the top surfaces of disc 15 and O-ring 26 extend above the top of closure surface 25. This is the condition illustrated in F [0, 2b for clarity of understanding. The stem of fastener passes through the hole 21 in leaf spring 16, then through O-ring 26, then through aperture 27 in closure 13. Rigid washer 30 is placed around the free end of stem 27.

Fastener terminal 20 clamps the leaf spring 16 against 0- ring 26 so that the bottom surface of spring 16 rests on the top surface of closure 13. To obtain uniform compression, the head portion 18 of fastener 20 and the leaf spring 16 are made wide enough to cover the compressed O-ring 31 and resilient disc 15. When spring 16 bottoms on surface 25, the entire assembly is secured together in the operating position by flaring the stem end 29 over washer 30. The hitherto loose parts are then clamped to closure 13 between the shoulder 17 and flared end portion 29 of fastener 20. Excessive tightness is avoided to permit rotation of the elongate spring 16.

When the assembly is completed as described, O-ring 26 is compressed between the bottom surface of spring 16 and the bottom surface of recess 31 and confined by the sides of recess 31 to form a permanent seal against the passage of any highpressure fluid attempting to escape from the container through the space between bore 27 and stem 28. In a similar manner the force exerted on resilient disc 15 by the end of spring 16 compresses the disc 15 which obstructs the vent ex haust end 32 to form a seal against the passage of high-pressure fluids at pressure levels below the critical threshold.

When the assembly is installed in the battery container as shown in HO. 1, washer lug makes electrical contact with cell connector 7 and the system is a completely self-contained hermetically sealed operating unit. In operation with successive discharging and recharging cycles objectionably high gas pressure may eventually build up. The spring constant of spring 16 and the dimensions and characteristics of resilient disc 15 and the other components of the system are such that the compression of the disc 15 around vent exit 33 establishes a tight seal for all allowable internal gas pressures in the battery. As the gas pressure continues to rise, it reaches a level which constitutes the critical threshold for which the spring force of resilient disc 15 has been designed. Any pressure in excess of this threshold lifts the underside of disc 15 away from the exit 33 whereby fluid is immediately released into A second embodiment of the present invention is illustrated in FIGS. 3a and-3b. Cylindrical recess 14a of FIG. 3b is deeper than the corresponding recess 14 of FIG. 2b, and vent hole 32a is correspondingly shorter for the same thickness of closure 13.'Resilient annular washer 15a, preferably ofneoprene. which is so receivedin recess 14a that the central aperture 38 is concentric with vent 32a. A hat-shaped plug 40, which may be of stainless steel, compresses washer 15a against the bottom of recess 140 under the restraining forceof spring 16, bearing upon the upwardly projecting peak of the hat, to maintain a fluid seal between the upper surface of washer 15a and the lower surface of the crimped base or brim 39 of plug member 40 for all allowable gas pressures. When the gas pressure becomes abnormally high in the container and therefore on the concave underside of plug member 40, the restraining force of spring 16 is exceeded and the seal between the crimped base 39 and washer 15a is broken whereupon highpressure gas escapes through recess 14 past spring 16, which has been lifted by the'pressure, and into the atmosphere. As in the previous embodiment, when the force of the internal pressure becomes less than the spring tension, the seal between washer 15a and crimped base 39 is reestablished.

ln HO. 4, a spherical resilient ball 42 which may be of neoprene replaces annular washer 15a and plug member 40. The walls of recess 14b which is concentric with vent hole 32!) constrain ball 42 to be concentric with vent hole 32b. The selfresealable seal in this embodiment is between the periphery of the vent exit 41 and ball 42. The operation is the same as described for FlGS. 2b and 3b.

lclaim:

1. A vent assembly for a container subject to internal gas pressure, comprising: I I

a closure member forming a seal across the top of the container, said closure member being provided with a through-going venthole terminating in a recess at the upper surface thereof;

resilient plug means in said recess obstructing said vent hole;

fastening means on said upper surface offset from said recess; and

an elongate spring separate and independent of said plug means pivotally engaged by said fastening means for rotation about the latter, said spring normally overlying said recess in cantilever fashion and exerting downward pressure upon said plug means for resisting the escape of gases through said vent hole, rotation of said spring into an off-normal position enabling withdrawal of said plug means and filling of the container through said vent hole.

2. A vent assembly as defined in claim 1 wherein said fastening means comprises a stem with a head rising from said closure member and resilient support means surrounding said recess 14 and the atmosphere, until the force created by the internal pressure becomes less than the spring force, at which time spring 16 and disc 15 come down again on vent exit 33 and reestablish the seal. This process continues over the life of the battery.

An important feature of my present improvement is its stem, said spring being traversed by said stem and being clamped between said head and said support means.

3. A vent assembly as defined in claim 2 wherein said plug means projects above said recess in its uncompressed state, said spring bearing upon said plug means with sufficient pressure to conic to rest against said upper surface outside said recess. I

4. A vent assembly as defined in claim 1 wherein said plug means has the shape of a disc substantially filling said recess.

5. A vent assembly as defined in claim 1 wherein said plug means has the shape of a sphere substantially filling said recess.

6. A vent assembly for a battery casing subject to internal gas pressure, comprising:

a closure member forming a seal across the top of the casing, said closure member being provided with a throughgoing vent hole terminating in a recess at the upper surface thereof and with a bore offset from said vent hole;

resilient plug means in said recess obstructing said vent hole; l

a terminal stud passing through said aperture in conductive contact with a battery component in said casing, said stud having a head above said upper surface;

' an elastic ring surrounding said stud below said head; and

an elongate spring separate and independent of said'plug means traversed by said stud and clamped between said ring and said head while being rotatable about said stud, with elastic deformation of said ring to seal said bore, said spring normally overlying said recess in cantilever fashion and exerting downward pressure upon said plug means for resisting the escape of gases through said vent hole, rotation of said spring into an off-normal position enabling withdrawal of said plug means and filling of the casing through said vent hole.

7. A vent assembly as defined in claim 6 wherein said bore terminates at its upper end in an annular depression receiving said ring.

, 8. A vent assembly as defined in claim 7 wherein said plug means projects above said recess in its uncompressed state,

said spring bearing upon said plug means with sufficient pres throughgoing vent hole terminating in a recess at the upper surface thereof;

a resilient plug in said recess obstructing said vent hole, said plug having a concave underside overlying said vent hole and a peak rising above said vent hole slightly beyond the level of said upper surface; I fastening means on said upper surface offset from said recess; and

an elongate spring engaged by said fastening means, said springoverlying said recess in cantilever fashion and exerting downward pressure upon said peak for resisting the escape of gases rising from said vent hole and accumulating in said concave underside.

10; A vent assembly as defined in claim 9, further comprising a resilient annular washer on the bottom of said recess, said plug being substantially hat shaped and provided with a crimped brim surrounding said vent hole and resting against the top of said washer.

11. A vent assembly for a battery casing subject to internal gas pressure, comprising:

a closure member forming a seal across the top of the casing, said closure member being provided with a throughgoing vent hole terminating in a recess at the upper surface thereof and with a bore offs'etfrom said vent hole;

; a resilient plug in said recess obstructing said vent hole, said plug having a concave underside overlying said vent hole and a peak rising above said vent hole substantially to the level of said upper surface;

a terminal stud passing through said aperture in conductive contact with a battery component in said casing, said stud having a head above said upper surface;

an elastic ring surrounding said stud below said head; and

an elongate spring traversed by said stud and clamped between said head and said ring with elasticdeformation of the latter to seal said bore, said spring overlying said recess in cantilever fashion and exerting downward pressure upon said peak for resisting the escape of gases rising from said vent hole and accumulating in said concave underside.

12. A vent assembly as defined in claim 11 wherein said bore terminates at its upper end in an annular depression receiving said ring, the latter being elastically deformed against the periphery of said depression.

13. A vent assembly for a container subject to internal gas pressure, comprising:

a closure member forming a seal across the top of the com tainer, said closure member being provided with a throughgoing vent hole terminating in a recess at the upper surface thereof;

a resilient plug in said recess obstructing said vent hole, said plug having a concave underside overlying said vent hole and a peak rising in line with said vent hole above said surface; 7

fastening means on said upper surface offset from said recess; and

an elongate spring pivotally engaged by said fastening means for rotation about the latter, said spring normally overlying said recess in cantilever fashion and exerting downward pressure upon said peak for resisting the escape of gases rising from said vent hole and accumulating in said concave underside.

14. A vent assembly for a battery casing subject to internal gas pressure, comprising:

a closure member forming a seal across the top of the casing, said closure member being provided with a throughgoing vent hole terminating in a recess at the upper surface thereof and with a bore offset from said vent hole terminating in an annular depression at said upper surface;

a resilient plug in said recess obstructing said vent hole, said plug having a concave underside bounded by a crimped base surrounding said vent hole and a peak rising in line with said vent hole above said upper surface;

a terminal stud passing through said aperture in conductive contact with a battery component in said casing, said stud having a head above said upper surface;

an elastic ring around said stud received in said depression;

and

an elongate spring traversed by said stud and clamped between said ring and said head while being rotatable about said stud, with elastic deformation of said ring against the periphery of said depression to seal said bore, said spring normally overlying said recess in cantilever fashion and exerting downward pressure upon said peak for resisting the escape of gases rising from said vent hole and accumulating in said concave underside. 

1. A vent assembly for a container subject to internal gas pressure, comprising: a closure member forming a seal across the top of the container, said closure member being provided with a through-going venthole terminating in a recess at the upper surface thereof; resilient plug means in said recess obstructing said vent hole; fastening means on said upper surface offset from said recess; and an elongate spring separate and independent of said plug means pivotAlly engaged by said fastening means for rotation about the latter, said spring normally overlying said recess in cantilever fashion and exerting downward pressure upon said plug means for resisting the escape of gases through said vent hole, rotation of said spring into an off-normal position enabling withdrawal of said plug means and filling of the container through said vent hole.
 2. A vent assembly as defined in claim 1 wherein said fastening means comprises a stem with a head rising from said closure member and resilient support means surrounding said stem, said spring being traversed by said stem and being clamped between said head and said support means.
 3. A vent assembly as defined in claim 2 wherein said plug means projects above said recess in its uncompressed state, said spring bearing upon said plug means with sufficient pressure to come to rest against said upper surface outside said recess.
 4. A vent assembly as defined in claim 1 wherein said plug means has the shape of a disc substantially filling said recess.
 5. A vent assembly as defined in claim 1 wherein said plug means has the shape of a sphere substantially filling said recess.
 6. A vent assembly for a battery casing subject to internal gas pressure, comprising: a closure member forming a seal across the top of the casing, said closure member being provided with a throughgoing vent hole terminating in a recess at the upper surface thereof and with a bore offset from said vent hole; resilient plug means in said recess obstructing said vent hole; a terminal stud passing through said aperture in conductive contact with a battery component in said casing, said stud having a head above said upper surface; an elastic ring surrounding said stud below said head; and an elongate spring separate and independent of said plug means traversed by said stud and clamped between said ring and said head while being rotatable about said stud, with elastic deformation of said ring to seal said bore, said spring normally overlying said recess in cantilever fashion and exerting downward pressure upon said plug means for resisting the escape of gases through said vent hole, rotation of said spring into an off-normal position enabling withdrawal of said plug means and filling of the casing through said vent hole.
 7. A vent assembly as defined in claim 6 wherein said bore terminates at its upper end in an annular depression receiving said ring.
 8. A vent assembly as defined in claim 7 wherein said plug means projects above said recess in its uncompressed state, said spring bearing upon said plug means with sufficient pressure to come to rest against said upper surface outside said recess while deforming said ring against the periphery of said depression.
 9. A vent assembly for a container subject to internal gas pressure, comprising: a closure member forming a seal across the top of the container, said closure member being provided with a throughgoing vent hole terminating in a recess at the upper surface thereof; a resilient plug in said recess obstructing said vent hole, said plug having a concave underside overlying said vent hole and a peak rising above said vent hole slightly beyond the level of said upper surface; fastening means on said upper surface offset from said recess; and an elongate spring engaged by said fastening means, said spring overlying said recess in cantilever fashion and exerting downward pressure upon said peak for resisting the escape of gases rising from said vent hole and accumulating in said concave underside.
 10. A vent assembly as defined in claim 9, further comprising a resilient annular washer on the bottom of said recess, said plug being substantially hat shaped and provided with a crimped brim surrounding said vent hole and resting against the top of said washer.
 11. A vent assembly for a battery casing subject to internal gas pressure, comprising: a closure member forming a seal across the top of the casing, saiD closure member being provided with a throughgoing vent hole terminating in a recess at the upper surface thereof and with a bore offset from said vent hole; a resilient plug in said recess obstructing said vent hole, said plug having a concave underside overlying said vent hole and a peak rising above said vent hole substantially to the level of said upper surface; a terminal stud passing through said aperture in conductive contact with a battery component in said casing, said stud having a head above said upper surface; an elastic ring surrounding said stud below said head; and an elongate spring traversed by said stud and clamped between said head and said ring with elastic deformation of the latter to seal said bore, said spring overlying said recess in cantilever fashion and exerting downward pressure upon said peak for resisting the escape of gases rising from said vent hole and accumulating in said concave underside.
 12. A vent assembly as defined in claim 11 wherein said bore terminates at its upper end in an annular depression receiving said ring, the latter being elastically deformed against the periphery of said depression.
 13. A vent assembly for a container subject to internal gas pressure, comprising: a closure member forming a seal across the top of the container, said closure member being provided with a throughgoing vent hole terminating in a recess at the upper surface thereof; a resilient plug in said recess obstructing said vent hole, said plug having a concave underside overlying said vent hole and a peak rising in line with said vent hole above said surface; fastening means on said upper surface offset from said recess; and an elongate spring pivotally engaged by said fastening means for rotation about the latter, said spring normally overlying said recess in cantilever fashion and exerting downward pressure upon said peak for resisting the escape of gases rising from said vent hole and accumulating in said concave underside.
 14. A vent assembly for a battery casing subject to internal gas pressure, comprising: a closure member forming a seal across the top of the casing, said closure member being provided with a throughgoing vent hole terminating in a recess at the upper surface thereof and with a bore offset from said vent hole terminating in an annular depression at said upper surface; a resilient plug in said recess obstructing said vent hole, said plug having a concave underside bounded by a crimped base surrounding said vent hole and a peak rising in line with said vent hole above said upper surface; a terminal stud passing through said aperture in conductive contact with a battery component in said casing, said stud having a head above said upper surface; an elastic ring around said stud received in said depression; and an elongate spring traversed by said stud and clamped between said ring and said head while being rotatable about said stud, with elastic deformation of said ring against the periphery of said depression to seal said bore, said spring normally overlying said recess in cantilever fashion and exerting downward pressure upon said peak for resisting the escape of gases rising from said vent hole and accumulating in said concave underside. 